391613 has 2 divisors, whose sum is σ = 391614. Its totient is φ = 391612.

The previous prime is 391579. The next prime is 391619. The reversal of 391613 is 316193.

391613 = 442² + 443².

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 196249 + 195364 = 443^2 + 442^2 .

It is an emirp because it is prime and its reverse (316193) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 391613 - 2¹⁸ = 129469 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391619) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195806 + 195807.

It is an arithmetic number, because the mean of its divisors is an integer number (195807).

2³⁹¹⁶¹³ is an apocalyptic number.

391613 is the 443-rd centered square number.

It is an amenable number.

391613 is a deficient number, since it is larger than the sum of its proper divisors (1).

391613 is an equidigital number, since it uses as much as digits as its factorization.

391613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 486, while the sum is 23.

The square root of 391613 is about 625.7899008453. The cubic root of 391613 is about 73.1620220645.

The spelling of 391613 in words is "three hundred ninety-one thousand, six hundred thirteen".